public class Example4_8 {
	public static void main (String args[]) {
	  Circle circle = new Circle();
	  circle.setRadius(10);
	  Circular circular = new Circular();
	  System.out.println("circle的引用:"+circle);
	  System.out.println("圆锥的bottom的引用:"+circular.bottom);
	  circular.setHeight(5);
	  circular.setBottom(circle);
	  System.out.println("circle的引用:"+circle);
	  System.out.println("圆锥的bottom的引用:"+circular.bottom);
	  System.out.println("圆锥的体积:"+circular.getVolme());
	  System.out.println("修改circle的半径，bottom的半径同样变化");
	  circle.setRadius(20);
	  System.out.println("bottom的半径:"+circular.getBottomRadius());
	  System.out.println("重新创建circle,circle的引用将发生变化");
	  circle = new Circle();
	  System.out.println("circle的引用:"+circle);
	  System.out.println("但是不影响circular的bottom的引用");
	  System.out.println("圆锥的bottom的引用:"+circular.bottom);
	}
}